package de.fub.bytecode.generic;

import de.fub.bytecode.Constants;
import java.io.*;

/** 
 * Wrapper class for push operations, which are implemented either as BIPUSH,
 * LDC or xCONST_n instructions.
 *
 * @version $Id: PUSH.java,v 1.1.1.1 2000/08/10 16:05:07 cvs Exp $
 * @author  <A HREF="http://www.inf.fu-berlin.de/~dahm">M. Dahm</A>
 */
public final class PUSH
  implements CompoundInstruction, VariableLengthInstruction, InstructionConstants
{
  private Instruction instruction;

  /**
   * @param cp Constant pool
   * @param value to be pushed 
   */
  public PUSH(ConstantPoolGen cp, double value) {
	if(value == 0.0)
	  instruction = DCONST_0;
	else if(value == 1.0)
	  instruction = DCONST_1;
	else // Create a Constant pool entry
	  instruction = new LDC2_W(cp.addDouble(value));
  }  
  /**
   * @param cp Constant pool
   * @param value to be pushed 
   */
  public PUSH(ConstantPoolGen cp, float value) {
	if(value == 0.0)
	  instruction = FCONST_0;
	else if(value == 1.0)
	  instruction = FCONST_1;
	else if(value == 2.0)
	  instruction = FCONST_2;
	else // Create a Constant pool entry
	  instruction = new LDC(cp.addFloat(value));
  }  
  /**
   * This constructor also applies for values of type short, char, byte 
   *
   * @param cp Constant pool
   * @param value to be pushed 
   */
  public PUSH(ConstantPoolGen cp, int value) {
	if((value >= -1) && (value <= 5)) // Use ICONST_n
	  instruction = INSTRUCTIONS[Constants.ICONST_0 + value];
	else if((value >= -128) && (value <= 127)) // Use BIPUSH
	  instruction = new BIPUSH((byte)value);
	else if((value >= -32768) && (value <= 32767)) // Use SIPUSH
	  instruction = new SIPUSH((short)value);
	else // If everything fails create a Constant pool entry
	  instruction = new LDC(cp.addInteger(value));
  }  
  /**
   * @param cp Constant pool
   * @param value to be pushed 
   */
  public PUSH(ConstantPoolGen cp, long value) {
	if(value == 0)
	  instruction = LCONST_0;
	else if(value == 1)
	  instruction = LCONST_1;
	else // Create a Constant pool entry
	  instruction = new LDC2_W(cp.addLong(value));
  }  
  /**
   * @param cp Constant pool
   * @param value to be pushed 
   */
  public PUSH(ConstantPoolGen cp, Boolean value) {
	this(cp, value.booleanValue());
  }  
  /**
   * @param cp Constant pool
   * @param value to be pushed 
   */
  public PUSH(ConstantPoolGen cp, Character value) {
	this(cp, (int)value.charValue());
  }  
  /**
   * @param cp Constant pool
   * @param value to be pushed 
   */
  public PUSH(ConstantPoolGen cp, Number value) {
	if((value instanceof Integer) || (value instanceof Short) || (value instanceof Byte))
	  instruction = new PUSH(cp, value.intValue()).instruction;
	else if(value instanceof Double)
	  instruction = new PUSH(cp, value.doubleValue()).instruction;
	else if(value instanceof Float)
	  instruction = new PUSH(cp, value.floatValue()).instruction;
	else if(value instanceof Long)
	  instruction = new PUSH(cp, value.longValue()).instruction;
	else
	  throw new ClassGenException("What's this: " + value);
  }  
  /**
   * @param cp Constant pool
   * @param value to be pushed 
   */
  public PUSH(ConstantPoolGen cp, String value) {
	if(value == null)
	  instruction = ACONST_NULL;
	else // Create a Constant pool entry
	  instruction = new LDC(cp.addString(value));
  }  
  /**
   * @param cp Constant pool
   * @param value to be pushed 
   */
  public PUSH(ConstantPoolGen cp, boolean value) {
	instruction = INSTRUCTIONS[Constants.ICONST_0 + (value? 1 : 0)];
  }  
  public final Instruction getInstruction() {
	return instruction;
  }  
  public final InstructionList getInstructionList() {
	return new InstructionList(instruction);
  }  
  /**
   * @return mnemonic for instruction
   */
  public String toString() {
	return instruction.toString() + " (PUSH)";
  }  
}